04876491 is referenced by 107 patents and cites 11 patents.

Control and synchronization of a polyphase, brushless DC motor (used for a hard-disk system) during initial start-up of the motor, is effected by monitoring rotor position using a high-frequency commutation: A short current pulse is applied to each power phase of the motor, and motor current conducted in response thereto, is measured to determine therefrom positional information of the rotor. From such positional information the identity of the appropriate motor phase to which is applied a torque-producing current is determined. Cycles of high-frequency commutation and application of torque-producing are performed, until the rotational speed of the rotor has attained a predetermined RPM. Motor speed is controled in synchronized, increasing fashion by continued monitoring of the motor current and back-EMF, until a desired rotational RPM is attained, whereupon torque-producing current is sequentially applied to each motor phase in synchronization with the rotor position by deriving positional information from the disk.

Title
Method and apparatus for brushless DC motor speed control
Application Number
880754
Publication Number
4876491
Application Date
February 26, 1988
Publication Date
October 24, 1989
Inventor
Louis J Shrinkle
Boulder
CO, US
John P Squires
Jamestown
CO, US
Agent
Fliesler Dubb Meyer & Lovejoy
Assignee
Conner Peripherals
CA, US
IPC
H02P 6/02
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